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Osteonevus of Nanta is a rare histopathologic variant of melanocytic nevus that results from ossification of the dermis between dermal nests of melanocytes. Most cases described in the literature have been associated with long-standing intradermal nevi and were often located in the upper part of the body. We report a lesion on the shoulder of an elderly man showing the association of a common blue nevus and osteoma cutis, an exceptional feature which has been previously reported in 2 instances. We also describe for the first time the dermoscopic appearance of this "blue osteonevus."

Juvenile xanthogranuloma is the most common form of non-Langerhans cell histiocytosis in childhood. The clinical differential diagnosis of a solitary juvenile xanthogranuloma includes molluscum contagiosum, Spitz nevus, and melanoma. Lesions larger than 2 cm in diameter may be misdiagnosed as hemangiomas, but this is not typical of smaller juvenile xanthogranuloma. We report a case of solitary juvenile xanthogranuloma in a 10-year-old boy with angiomatous appearance and peculiar immunophenotype.

Paraneoplastic syndromes consist of a group of disorders that are not related to the extension of the primary tumor or its metastases and that might be the first manifestation of a hidden neoplasm. It is a well-known association between dermatomyositis (DM) and cancer, especially gynecological tumors in women and lung cancer in men.We describe the case of a 67-year-old male who developed muscular weakness and pruritic skin lesions. Skin biopsies were performed and histologic findings were consistent with DM.Skin biopsy showed interface dermatitis with vacuolar degeneration of the basal layer, dermal mucin deposits, and necrotic keratinocytes in the acrosyringia, a finding that has been previously reported in lupus erythematous but not in DM. Autoimmunity tests showed positivity for antinuclear antibodies and anti-NXP2, a recently described antibody associated with juvenile DM and, more rarely, with paraneoplastic DM.We present the first case in the literature with histopathologic changes of DM affecting the acrosyringia. Besides, our patient autoimmunity results support the utility of the new myositis-specific autoantibodies and its relation with a clinical phenotype.